The accumulation of medical evidence in recent years regarding the adverse health implications of high fat diets, principally heart attacks, arteriosclerosis and obesity, has caused consumers to become extremely concerned about their diets. It is estimated that between 70-80% of U.S. adult females follow a weight reducing diet at least once a year. Men are also concerned about their weight and cholesterol levels.
Common obesity is currently one of the most prevalent metabolic problems in the general population. Fats and oils are necessary for balanced nutrition. However, the average consumer simply consumes more than is needed for proper nutrition. It is estimated that lipids constitute about 40% of the total calories in the typical Western diet. Fats are consumed directly in meats, spreads, salad oils, and in natural produce such as nuts and avocados. Fats and oils are also consumed as a result of absorption or incorporation in foods during baking and frying. The sharp increase in consumption of fast foods is a major contributor to the increase in the amount of dietary fat since fast foods rely extensively on frying processes employing fats and oils. In addition, the snack food industry uses large amounts of fats and oils in the production of potato chips, corn chips and other snack items.
It is clear that there is an enormous potential market for a fat substitute or fat mimetic that is substantially non-digestible or has reduced caloric value. Replacement of fats in the diet with non-caloric substitutes is a more efficient way of reducing caloric intake than replacing sugar or carbohydrates because, gram for gram, the substitution of non-caloric fat substitutes is more than twice as effective as reducing carbohydrate content with substances such as saccharine or aspartame.
One of the difficulties is eliminating fat from the diet is the fact that fats and oils are all-pervasive in food products. In part, this is because they play an important role in the organoleptic acceptability of food products. Generally speaking, a fat substitute providing fewer calories than a conventional triglyceride muse be non-digestible, that is, not hydrolyzed in the digestive tract. In addition, it should not be directly absorbed through the intestinal wall. While some types of fat substitutes may be non-digestible, they are not of sufficiently high molecular weight to prevent them from being absorbed through the intestinal wall. The threshold molecular weight of non-absorbability for lipophilic molecules appears to be about 600.
In addition, the fat substitute must itself be non-toxic at high levels of ingestion. It must contain no toxic residues or impurities. To the extent that a fat substitute may be partially hydrolyzed in the digestive tract, any hydrolysis products must be non-toxic and/or metabolizable. If metabolizable, they should have very low caloric value and toxicity. In general, fat substitutes must be without any serious physiological side effects.
A fat substitute must also have good organoleptic qualities of mouth feel and must not unacceptable alter the taste of food composition. In addition, fat substitutes must have appropriate physical properties for use in food compositions. For example, they should be liquids or low-melting solids depending on whether they are to be used as oil or shortening substitutes.
Another important requirement for a fat mimetic is sufficient resistance to oxidative and thermal degradation at elevated temperatures to permit the use of the fat mimetic in deep fat frying applications and other cooking applications. Among the problems which can result if a lipid is exposed to high temperatures for an extended period of time are discoloration, smoking, generation of volatile decomposition products, development of off-flavors and unacceptable odor, thickening or gelling due to cross-linking or polymer formation, production of toxic by-products, and so forth. Certain fat substitutes such as those derived from proteinaceous materials are not suitable for use in cooking since their fat-like properties are destroyed upon exposure to heat. Other fat substitutes, such as the esterified epoxide-extended polyols described in U.S. Pat. No. 4,861,613 , are considerably more stable and thus are generally suitable for use in the preparation of cooked food. However, such compounds are still somewhat susceptible to degradation under severe conditions owing to the presence of readily-abstractable tertiary hydrogens in the poly(oxypropylene)segments of these materials. Thus, it would be highly desirable to obtain fat mimetics which are even more resistant to heat than esterified epoxide-extended polyols without sacrificing the desirable characteristics of low digestibility and fat-like properties exhibited by such substances.